1. Field of the Invention
The present invention is directed to decorating fingernails by inkjet printing or sputtering. More particularly, there is provided a process and apparatus utilizing inkjet printing and sputtering technology to create an aesthetic appearance to nails.
Fingernails have been decorated to provide an aesthetic appearance or to provide a message. In the past, fingernails were tattooed or lasered to provide a decoration.
Tattooing is usually performed with a press-on decal or manually painting. Lasering usually requires the use of skilled people.
There presently exists a need to provide a technology which can satisfy the fashion needs of the population without fear of injury and can be rapidly and accurately performed.
Inkjets use thermal or piezoelectric technology. In thermally driven inkjets, heat is used to drive ink onto a substrate. There are three main stages with this method. The squirt is initiated by heating the ink to create a bubble until the pressure forces it to burst and hit the paper to form a dot. The bubble then collapses as the element cools, and the resulting vacuum draws ink from the reservoir to replace the ink that was ejected.
Thermal inkjets have print heads containing between 300 and 600 nozzles in total, each about the diameter of a human hair (approx. 70 microns). Tiny heating elements are used to eject ink droplets from the print-head's nozzles. These nozzles deliver drop volumes of around 8-12 picolitres (a picolitre is a million millionth of a liter), and dot sizes of between 50 and 60 microns in diameter. By comparison, the smallest dot size visible to the naked eye is around 30 microns. Dye-based cyan, magenta and yellow (CMY) inks are normally delivered via a combined CMY print-head. Several small color ink drops--typically between four and eight can be combined to deliver a variable dot size, a bigger palette of non-halftoned colors and smoother halftones. Black ink, which is generally based on bigger pigment molecules, is delivered from a separate print-head in larger drop volumes of around 35 pt. Nozzle density, corresponding to the printer's native resolution, varies between 300 and 600 dots per inch (dpi), with enhanced resolutions of 1200 dpi increasingly available. Print speed is chiefly a function of the frequency with which the nozzles can be made to fire ink drops and the width of the swath printed by the printhead. Typically this is around 12 MHz and half an inch respectively, giving print speeds of between 4 to 6 ppm (pages per minute) for monochrome text and 2 to 4 ppm for color text and graphics.
A piezoelectric inkjet uses a piezo crystal at the back of the ink reservoir. This is rather like a loudspeaker cone--it flexes when an electric current flows through it. So, whenever a dot is required, a current is applied to the piezo element, the element flexes and in so doing forces a drop of ink out of the nozzle.
There are several advantages to the piezo method. The process allows more control over the shape and size of ink droplet release. The tiny fluctuations in the crystal allow for smaller droplet sizes and hence higher nozzle density. Also, unlike with thermal technology, the ink does not have to be heated and cooled between each cycle. This saves time, and the ink itself is tailored more for its absorption properties than its ability to withstand high temperatures. This allows more freedom for developing new chemical properties in inks.
Washable tattoos are commercially sold which are applied to both toenails and fingernails. However, such tattoos are not useful or are lost at the beach or swimming pools.
U.S. Pat. No. 5,782,249 to Weber et al, which is herein incorporated by reference, discloses a process for decorating fingernails using laser irradiation.
U.S. Pat. No. 5,541,630 to Yasushi et al, which is herein incorporated by reference, discloses one form of inkjets printing head which can be utilized in the present invention.
U.S. Pat. Nos. 4,521, 788, 4,115, 789, 5,121,132 and 4,158,847, discloses inkjet printing heads and apparatuses which may be used in the present invention.
Therefore, it can be appreciated that there exists a continuing need for a new and improved simple and economical process for decorating fingernails which can be used commercially, as well as, for home use to obtain similar results. In this regard, the present invention substantially fulfills this need.
It is understood that the term "fingernails" also relates to toenails.